Electrode for an electrophoresis painting installation

ABSTRACT

An electrode, in particular for an electrophoresis painting installation. The metal conductor has threaded thereon a row of rigid beads constituting a flexible insulating sheath. The beads are maintained at both ends of the conductor in such manner that they are constantly in contact with each other. At least some of the beads have passages putting the conductor in communication with the exterior of the sheath.

United States Patent Esselin et al.

[54] ELECTRODE FOR AN ELECTROPHORESIS PAINTING INSTALLATION [72] Inventors: Raymond Esselin, valentign y; Jean- Claude Poirier, Grand-Charmont, both of France [73] Assignees: Automobiles Peugeot, Paris; Regle Nationale Des Usines Renault, Billancourt, France [22] Filed: Apr.21, 1970 [21] Appl.No.: 30,537

[30] Foreign Application Priority Data May 7, 1969 [52] US. Cl ..204/280, 204/299, 204/300,

204/DIG. 7 [51] lnt.Cl. ..B01r 3/02,C23b 5/72,B01d 15/02 [58] Field of Search ..204/l81, 299, 300, 280, DIG. 7

France 6914555 [451 Mar. 28, 1972 [56] References Cited UNITED STATES PATENTS 3,325,390 6/1967 Burnside et al. ..204/300 X 2,106,004 1/1938 Inglee ..204/280 3,527,685 9/1970 Anderson... ....204/280 X 1,881,713 10/1932 Laukel ..204/D1G. 7 3,476,667 11/1969 Gilchrist ..204/1 81 Primary Examiner-John H. Mack Assistant Examiner-R. J. Fay Attorney-Bums, Doane, Benedict, Swecker & Mathis [57] ABSTRACT An electrode, in particular for an electrophoresis painting installation. The metal conductor has threaded thereon a row of rigid beads constituting a flexible insulating sheath. The beads are maintained at both ends of the conductor in such manner that they are constantly in contact with each other. At least some of the heads have passages putting the conductor in communication with the exterior of the sheath.

1] Claims, 2 Drawing Figures ELECTRODE FOR AN ELECTROPI'IORESIS PAINTING INSTALLATION The present invention relates to electrophoresis painting installations and more particularly to the electrode employed in such installations.

It is known that in an installation applying paint by the electrophoresis effect, the part to be painted is dipped in an immersion bath which contains the paint and is brought to a negative potential, the part being brought to a positive potential. When the part has hollow or semi-hollow portions, as is the case for example in automobile vehicle bodies, it is necessary to employ additional negative electrodes which are placed in these hollow portions so as to produce a more intense electric field in these zones whereby coating of suitable thickness can be deposited therein. Indeed, if these electrodes are not employed, the field in the hollow parts is too weak and the thickness of the paint deposited insufficient. At the present time, these electrodes are formed by a metal conductor of steel or copper surrounded by a sheath of perforated plastics material, this conductor being flexible or rigid and having a length suitable for the contemplated utilization. The conductor constitutes the active part of the electrode and the sheath must afford effective insulation between the conductor and the part to be painted (since the difference of potential between these two elements can be several hundred volts) while allowing the conductor to be in constant contact with the paint. Conventional sheaths employed up to the present time are of perforated polyvinyl chloride or woven from threads of products known as Tergal, Nylon, Rilsan, or the like, so that the paint can pass therethrough. In both cases, these sheaths have a serious drawback, namely their weakness or fragility. The electrode is introduced in the hollow portions of the part to be painted by way of small orifices which are usually formed in a sheet having sharp edges. Consequently, the sheath which rubs against this sheet very rapidly deteriorates with risk of short circuiting and a materially increased cost of the operation.

The object of the invention is to remedy this drawback.

The invention provides an electrode, in particular for an electrophoresis paint applying installation comprising a metal conductor and an insulating sheath, wherein said sheath comprises a series of rigid annular members threaded onto the conductor and maintained at both ends of the latter in such manner as to be constantly in contact with each other, at least some of said members having passages putting the interior and exterior of the sheath in communication with each other.

The fact that the sheath is constituted by adjoining members and not by a roughly continuous layer of material, enables these members to be constructed from an insulating material of great strength while the sheath as a whole remains suitably flexible. Further, these members can be very thick and this still more prolongs the life of the electrode.

Further features and advantages of the invention will be aparent from the ensuing description with reference to the accompanying drawing.

In the drawing:

FIG. 1 is a perspective view, with a part cut away, of an electrode according to the invention, and

FIG. 2 is an'axial sectional view of a member of the electrode sheath shown in FIG. 1.

The drawing shows an electrode E which is of utility in an electrophoresis painting installation, the parts to be painted before for example automobile vehicle bodies.

The electrode E comprises a metal conductor 1 constituted for example by a steel cable whose end 1a carries a terminal 2 which can be secured thereto in any suitable manner. The other end 1b of the cable is fixed or riveted in an end collar 3.

Encompassingthis cable is an insulating sheath generally designated by the reference numeral 4 and formed by annular members or beads which are threaded on the cable and maintained in adjoining relation by a spring 5 so that they constitute a continuous sheath. The spring 5 bears through two washers 6a and 6b against the terminal 2 and against the adjoining end member or head respectively.

In the illustrated sheath, three different types of beads or members are provided, namely normal or standard members 7a and 7b, and an end bead 7c, thebeads 7a and 7b differing merely in that the beads 7a have notches 8 which allow communication between the interior and exterior of the sheath. Apart from this difference, the beads 7a and 7b are formed by a sleeve of rigid plastics material whose inner face is tapered. The thinner end 9b of each sleeve has a concaveshaped portion whereas the thicker end 90 has a corresponding convex-shaped portion. These portions may be part-spherical rings. The end bead 70 has a stepped bore or aperture whose small-diameter portion 7a surrounds the cable 1 and whose large-diameter portion 10b receives the retaining collar 3 which abuts against a shoulder 106 on the bead. The portion 10b has a length substantially greater than that of the collar 3 so as to perfectly insulate the collar and the end lb of the conductor cable. If desired, the free space in the aperture portion 10b is filled after assembly with a resin 11, for example the product known as Araldite.

This electrode is employed in the same way as conventional electrodes, that is, it is introduced through apertures of sometimes small size in the hollow or semi-hollow portions of the part to be painted prior to immersion in the bath of paint. Upon immersion, the paint enters the sheath by way of the notches 8 and this produces an electric field which is sufficient to insure migration of the particles of paint to the part to be painted which is brought to a positive potential. In will be understood that the size and the number of these notches are so chosen as to achieve an appropriate electric exchange.

Owing to its construction, the sheath 4 can be deformed and bent without baring parts of the metal cable 1 which could produce short circuiting. This is due mainly to the great thickness of the wall of each bead, particularly in the portion 9c which insures a constant coverage of the cable and contact between two adjacent beads. The complementary concave and convex shapes also facilitate the articulation between the beads whereas the tapered shape of the bore 90 of the bead improves the flexibility of the assembly. Indeed, it will be understood that if this hollow bore or aperture were cylindrical, with an inside diameter equal to the smaller diameter of the illustrated aperture and identical outside dimensions of the beads, in the course of bending of the electrode the edge of the bead would come in contact with the cable 1 sooner and this would limit the curvature to which the sheath could be bent.

The spring 5 ensures that the beads remain in adjoining relation and is designed to exert sufficient pressure, even in the event of accidental breakage of one of the beads of the sheath.

The beads are constructed from a rigid insulating material which stands up to electrophoresis painting conditions, for example polyoxymethylene or one of its copolymers, polyamide or any other suitable thermoplastic or thermosetting material. However, it is preferable that the melting temperature of the material of the beads be lower than the temperature reached in the paint drying oven in which the painted part is placed after removal of the electrodes. Indeed, in the event of the metal conductor accidentally breaking or the end bead being pulled off, the beads remaining in the hollow body would produce noise, so that their melting with adherence to the sheet of metal is a simple way of overcoming this drawback.

The electrode just described has an essential advantage over conventional electrodes. This advantage resides in its great strength due to the fact that the beads forming the sheath can be constructed from very thick rigid plastics material while they afford the sheath, if desired, a flexibility comparable to that of conventional sheaths, this flexibility depending partly on the force exerted by the spring 5. The sheath of this electrode is much stronger not only in its centre part but also at the end opposed to the terminal 2. In conventional flexible or rigid electrodes, the sheath has a tendency to break in this zone and bare the conductor. With the electrode according to the invention, owing to the presence of the end bead 7c, of the skirt it forms beyond the end collar 3, and of the additional protection afiorded by the resin 11, this end of the conductor is perfectly insulated without the sheath having particular rigidity in this zone. The electrode according to the invention is at least times more durable than that of conventional electrodes. This constitutes a substantial progress.

Although a specific embodiment of the invention has been described, many modifications and changes may be made therein without departing from the scope of the invention as defined in the appended claims.

Having now described our invention what we claim and desire to secure by Letters Patent is:

1. An electrode, in particular for an electrophoresis painting installation, having a metal conductor and an insulating sheath said sheath comprising a series of rigid annular insulating members in threaded relation to the conductor and maintained at both ends of the conductor so that said members are constantly in contact with each other, some of said members having passages putting the conductor in communication with the exterior of the sheath.

2. An electrode as claimed in claim 1, comprising two retaining elements respectively fixed to the ends of the metal conductor, and elastically yieldable means interposed between one of said retaining elements and an adjacent one of said members,

3. An electrode as claimed in claim 2, wherein one of said retaining elements comprises a collar secured to an end of the conductor, and the other retaining element is an electrical connecting terminal.

4. An electrode, in particular for an electrophoresis painting installation, having a metal conductor and an insulating sheath, said sheath comprising a series of rigid annular insulating members in threaded relation to the conductor and maintained at both ends of the conductor so that said members are constantly in contact with each other, some of said members having passages putting the conductor in communication with the exterior of the sheath, and each of said members is a bead having a generally substantially cylindrical outside shape and a tapered aperture for said conductor.

5. An electrode, in particular for an electrophoresis painting installation, having a metal conductor and an insulating sheath, said sheath comprising a series of rigid annular insulating members in threaded relation to the conductor and maintained at both ends of the conductor so that said members are constantly in contact with each other, some of said members having passages putting the conductor in communication with the exterior of the sheath, each member having end faces which are respectively concave and convex and have complementary shapes.

6. An electrode as claimed in claim 5, wherein said concave and convex faces are part-spherical.

7. An electrode, in particular for an electrophoresis painting installation, having a metal conductor and an insulating sheath, said sheath comprising a series of rigid annular insulating members in threaded relation to the conductor, two retaining elements respectively fixed to the ends of the metal conductor, and elastically yieldable means interposed between one of said retaining elements and an adjacent one of said members, whereby said members are constantly in contact with each other, some of said members having passages putting the conductor in communication with the exterior of the sheath, one of said end members immediately adjacent the retaining element secured to an end of the conductor having a portion extending beyond the end of the conductor and the corresponding retaining element.

8. An electrode as claimed in claim 7, wherein said portion of the member is filled with an insulating substance.

9. An electrode as claimed in claim 1, wherein said passages are notches in each portions of the members.

10. An electrode as claimed in claim ll, wherein said members are of insulating plastics material having a melting point lower than the temperature to which the part to be painted is brought during the subsequent drying operation.

11. An electrode as claimed in claim ll, wherein said members are of insulating plastics material having a melting point lower than C. 

1. An electrode, in particular for an electrophoresis painting installation, having a metal conductor and an insulating sheath said sheath comprising a series of rigid annular insulating members in threaded relation to the conductor and maintained at both ends of the conductor so that said members are constantly in contact with each other, some of said members having passages putting the conductor in communication with the exterior of the sheath.
 2. An electrode as claimed in claim 1, comprising two retaining elements respectively fixed to the ends of the metal conductor, and elastically yieldable means interposed between one of said retaining elements and an adjacent one of said members.
 3. An electrode as claimed in claim 2, wherein one of said retaining elements comprises a collar secured to an end of the conductor, and the other retaining element is an electrical connecting terminal.
 4. An electrode, in particular for an electrophoresis painting installation, having a metal conductor and an insulating sheath, said sheath comprising a series of rigid annular insulating members in threaded relation to the conductor and maintained at both ends of the conductor so that said members are constantly in contact with each other, some of said members having passages putting the conductor in communication with the exterior of the sheath, and each of said members is a bead having a generally substantially cylindrical outside shape and a tapered aperture for said conductor.
 5. An electrode, in particulaR for an electrophoresis painting installation, having a metal conductor and an insulating sheath, said sheath comprising a series of rigid annular insulating members in threaded relation to the conductor and maintained at both ends of the conductor so that said members are constantly in contact with each other, some of said members having passages putting the conductor in communication with the exterior of the sheath, each member having end faces which are respectively concave and convex and have complementary shapes.
 6. An electrode as claimed in claim 5, wherein said concave and convex faces are part-spherical.
 7. An electrode, in particular for an electrophoresis painting installation, having a metal conductor and an insulating sheath, said sheath comprising a series of rigid annular insulating members in threaded relation to the conductor, two retaining elements respectively fixed to the ends of the metal conductor, and elastically yieldable means interposed between one of said retaining elements and an adjacent one of said members, whereby said members are constantly in contact with each other, some of said members having passages putting the conductor in communication with the exterior of the sheath, one of said end members immediately adjacent the retaining element secured to an end of the conductor having a portion extending beyond the end of the conductor and the corresponding retaining element.
 8. An electrode as claimed in claim 7, wherein said portion of the member is filled with an insulating substance.
 9. An electrode as claimed in claim 1, wherein said passages are notches in end portions of the members.
 10. An electrode as claimed in claim 1, wherein said members are of insulating plastics material having a melting point lower than the temperature to which the part to be painted is brought during the subsequent drying operation.
 11. An electrode as claimed in claim 1, wherein said members are of insulating plastics material having a melting point lower than 180* C. 